This invention relates generally to a heat saving device for use in connection with a thermostatically controlled combustion chamber and particularly to a flue control assembly for reducing the amount of heat lost during the operation of the combustion chamber.
Most combustion chambers such as ovens, furnaces, water heaters and the like are supplied with heat intermittently by thermostatically controlled burners which are cut off when the desired temperature is achieved within the chamber and reactivated when the temperature falls below a predetermined level.
When the burners are operating in a combustion chamber it is necessary to allow the heated air to escape and flues are provided for this purpose. However, when the burners are not operating there is no need for a flue draft and, in fact, the flue draft is responsible for considerable heat loss. Most heating devices have a comparatively short burning cycle, for example the burners of a domestic furnace heater burn for considerably less than half of the time, those of a baking oven for somewhat more. Thus, if the flue is maintained in an open condition when the burners are not operating, a considerable amount of heat is drawn up the flue and wasted. Further, the draft tends to cause a problem by sucking out the pilot light in those instances in which gas or oil burners are used.
Various attempts have been made to conserve fuel and prevent the escape of heat from the combustion chamber when the burners are not operating by providing some means of closing the flue damper temporarily during these periods. Ideally, the requirements of such a flue control device are that it must open and close the damper automatically and effectively so that the damper cannot be in the closed position when the burner is operating. In addition, the operation of the device should be quiet and should be fairly rapid in its operation.
Several attempts have been made to provide an effective flue damper control but none appears to have met with general commercial acceptance. U.S. Pat. No. 2,165,488 issued to Klimis discloses a device for use with an oil furnace and depends upon a solenoid operated rack and pinion control. The damper is smaller than the flue for safety reasons so that the flue cannot be fully closed. U.S. Pat. No. 3,090,558 issued to Vaughn also discloses a flue damper control for oil furnaces the damper being operated by a reversing electric motor which is too slow for most operations.
The present flue control assembly solves the above and other problems in a manner not disclosed in the known prior art.